The locus coeruleus () (LC), also spelled locus caeruleus or locus ceruleus, is a nucleus in the

pons The pons (from Latin , "bridge") is part of the brainstem that in humans and other bipeds lies inferior to the midbrain, superior to the medulla oblongata and anterior to the cerebellum. The pons is also called the pons Varolii ("bridge of ...

of the

brainstem The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is ...

involved with

physiological Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemica ...

responses to stress and

panic Panic is a sudden sensation of fear, which is so strong as to dominate or prevent reason and logical thinking, replacing it with overwhelming feelings of anxiety and frantic agitation consistent with an animalistic fight-or-flight reac ...

. It is a part of the reticular activating system. The locus coeruleus, which in Latin means "blue spot", is the principal site for brain synthesis of

norepinephrine Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical in the catecholamine family that functions in the brain and body as both a hormone and neurotransmitter. The name "noradrenaline" (from Latin '' ad ...

(noradrenaline). The locus coeruleus and the areas of the body affected by the norepinephrine it produces are described collectively as the locus coeruleus-noradrenergic system or LC-NA system. Norepinephrine may also be released directly into the blood from the adrenal medulla.

Anatomy

The locus coeruleus (LC) is located in the posterior area of the rostral

in the lateral floor of the fourth ventricle. It is composed of mostly medium-size

neurons A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. ...

. Melanin granules inside the neurons of the LC contribute to its blue colour. Thus, it is also known as the nucleus pigmentosus pontis, meaning "heavily pigmented nucleus of the pons." The neuromelanin is formed by the

polymerization In polymer chemistry, polymerization (American English), or polymerisation (British English), is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are many fo ...

of norepinephrine and is analogous to the black

dopamine Dopamine (DA, a contraction of 3,4-dihydroxyphenethylamine) is a neuromodulatory molecule that plays several important roles in cells. It is an organic chemical of the catecholamine and phenethylamine families. Dopamine constitutes about 8 ...

-based neuromelanin in the substantia nigra. In adult humans (19-78) the locus coeruleus has 22,000 to 51,000 total pigmented neurons that range in size between 31,000 and 60,000 μm³.

Connections

The projections of this nucleus reach far and wide. For example, they innervate the

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spin ...

, the brain stem,

cerebellum The cerebellum (Latin for "little brain") is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as or even larger. In humans, the cere ...

hypothalamus The hypothalamus () is a part of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamus ...

, the thalamic relay nuclei, the

amygdala The amygdala (; plural: amygdalae or amygdalas; also '; Latin from Greek, , ', 'almond', 'tonsil') is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain's cerebrum in complex v ...

, the basal

telencephalon The cerebrum, telencephalon or endbrain is the largest part of the brain containing the cerebral cortex (of the two cerebral hemispheres), as well as several subcortical structures, including the hippocampus, basal ganglia, and olfactory bulb ...

, and the cortex. The norepinephrine from the LC has an excitatory effect on most of the brain, mediating arousal and priming the brain's neurons to be activated by stimuli. As an important homeostatic control center of the body, the locus coeruleus receives afferents from the hypothalamus. The cingulate gyrus and the amygdala also innervate the LC, allowing emotional pain and stressors to trigger noradrenergic responses. The cerebellum and afferents from the raphe nuclei also project to the LC, in particular the

pontine raphe nucleus The pontine raphe nucleus is one of the raphe nuclei. It is located in the pontine tegmentum Pontine may refer to: * Having to do with the pons, a structure located in the brain stem (from ''pons'', "bridge") * Pontine Marshes, a region of Ita ...

and dorsal raphe nucleus.

Inputs

The locus coeruleus receives inputs from a number of other brain regions, primarily: *The

Medial Medial may refer to: Mathematics * Medial magma, a mathematical identity in algebra Geometry * Medial axis, in geometry the set of all points having more than one closest point on an object's boundary * Medial graph, another graph that re ...

prefrontal cortex In mammalian brain anatomy, the prefrontal cortex (PFC) covers the front part of the frontal lobe of the cerebral cortex. The PFC contains the Brodmann areas BA8, BA9, BA10, BA11, BA12, BA13, BA14, BA24, BA25, BA32, BA44, BA45, BA ...

, whose connection is constant, excitatory, and increases in strength with raised activity levels in the subject *The

Nucleus paragigantocellularis The nucleus paragigantocellularis (nPGi) is a part of the brain, located in the rostral ventral medulla. It is a key brainstem region involved in the expression of cardiovascular and respiratory changes that occur following sympathetic activation ...

, which integrates autonomic and

environment Environment most often refers to: __NOTOC__ * Natural environment, all living and non-living things occurring naturally * Biophysical environment, the physical and biological factors along with their chemical interactions that affect an organism or ...

al stimuli *The Nucleus prepositus, which is involved in gaze *The Lateral hypothalamus, which releases orexin, which, as well as its other functions, is excitatory in the locus coeruleus.

Outputs

The projections from the locus coeruleus consist of neurons that utilize norepinephrine as their primary neurotransmitter. These projections include the following connections: :* LC →

Amygdala The amygdala (; plural: amygdalae or amygdalas; also '; Latin from Greek, , ', 'almond', 'tonsil') is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain's cerebrum in complex v ...

and

Hippocampus The hippocampus (via Latin from Greek , ' seahorse') is a major component of the brain of humans and other vertebrates. Humans and other mammals have two hippocampi, one in each side of the brain. The hippocampus is part of the limbic system, ...

:* LC →

Brain stem The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is cont ...

and

Spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spin ...

:* LC →

Cerebellum The cerebellum (Latin for "little brain") is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as or even larger. In humans, the cere ...

:* LC →

Cerebral cortex The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consisting o ...

:* LC →

Hypothalamus The hypothalamus () is a part of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamus ...

:* LC → Tectum :* LC →

Thalamus The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all direction ...

:* LC → Ventral tegmental area

Function

It is related to many functions via its widespread projections. The LC-NA system modulates cortical, subcortical, cerebellar, brainstem, and spinal cord circuits. Some of the most important functions influenced by this system are: * Arousal and sleep-wake cycle *

Attention Attention is the behavioral and cognitive process of selectively concentrating on a discrete aspect of information, whether considered subjective or objective, while ignoring other perceivable information. William James (1890) wrote that "Att ...

and

memory Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered ...

* Behavioral and cognitive flexibility,

creativity Creativity is a phenomenon whereby something new and valuable is formed. The created item may be intangible (such as an idea, a scientific theory, a musical composition, or a joke) or a physical object (such as an invention, a printed literary w ...

, behavioral inhibition and

stress (psychological) In psychology, stress is a feeling of emotional strain and pressure. Stress is a type of psychological pain. Small amounts of stress may be beneficial, as it can improve athletic performance, motivation and reaction to the environment. Exc ...

Cognitive control In cognitive science and neuropsychology, executive functions (collectively referred to as executive function and cognitive control) are a set of cognitive processes that are necessary for the cognitive control of behavior: selecting and su ...

Decision making In psychology, decision-making (also spelled decision making and decisionmaking) is regarded as the cognitive process resulting in the selection of a belief or a course of action among several possible alternative options. It could be either ra ...

and utility maximization * Emotions *

Neuroplasticity Neuroplasticity, also known as neural plasticity, or brain plasticity, is the ability of neural networks in the brain to change through growth and reorganization. It is when the brain is rewired to function in some way that differs from how it ...

* Posture and balance The locus coeruleus is a part of the reticular activating system, and is almost completely inactivated in rapid eye movement sleep.

Pathophysiology

The locus coeruleus may figure in

clinical depression Major depressive disorder (MDD), also known as clinical depression, is a mental disorder characterized by at least two weeks of pervasive low mood, low self-esteem, and loss of interest or pleasure in normally enjoyable activities. Introdu ...

panic disorder Panic disorder is a mental and behavioral disorder, specifically an anxiety disorder characterized by reoccurring unexpected panic attacks. Panic attacks are sudden periods of intense fear that may include palpitations, sweating, shaking, ...

Parkinson's disease Parkinson's disease (PD), or simply Parkinson's, is a long-term degenerative disorder of the central nervous system that mainly affects the motor system. The symptoms usually emerge slowly, and as the disease worsens, non-motor symptoms becom ...

, Alzheimer's disease and

anxiety Anxiety is an emotion which is characterized by an unpleasant state of inner turmoil Turmoil may refer to: * ''Turmoil'' (1984 video game), a 1984 video game released by Bug-Byte * ''Turmoil'' (2016 video game), a 2016 indie oil tycoon video ...

. Some medications including

norepinephrine reuptake inhibitor A norepinephrine reuptake inhibitor (NRI, NERI) or noradrenaline reuptake inhibitor or adrenergic reuptake inhibitor (ARI), is a type of drug that acts as a reuptake inhibitor for the neurotransmitters norepinephrine (noradrenaline) and epine ...

s ( reboxetine, atomoxetine), serotonin-norepinephrine reuptake inhibitors ( venlafaxine, duloxetine), and norepinephrine-dopamine reuptake inhibitors ( bupropion) are believed to show efficacy by acting upon

neuron A neuron, neurone, or nerve cell is an membrane potential#Cell excitability, electrically excitable cell (biology), cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous ...

s in this area. Research continues to reveal that

(NE) is a critical regulator of numerous activities from stress response, the formation of memory to attention and arousal. Many neuropsychiatric disorders precipitate from alterations to NE modulated neurocircuitry: disorders of affect, anxiety disorders, PTSD, ADHD and Alzheimer's disease. Alterations in the locus coeruleus (LC) accompany dysregulation of NE function and likely play a key role in the pathophysiology of these neuropsychiatric disorders.

In stress

The locus coeruleus is responsible for mediating many of the sympathetic effects during stress. The locus coeruleus is activated by stress, and will respond by increasing norepinephrine secretion, which in turn will alter cognitive function (through the prefrontal cortex), increase motivation (through nucleus accumbens), activate the hypothalamic-pituitary-adrenal axis, and increase the sympathetic

discharge Discharge may refer to Expel or let go * Discharge, the act of firing a gun * Discharge, or termination of employment, the end of an employee's duration with an employer * Military discharge, the release of a member of the armed forces from serv ...

/inhibit parasympathetic tone (through the

). Specific to the activation of the hypothalamic-pituitary adrenal axis, norepinephrine will stimulate the secretion of corticotropin-releasing factor from the hypothalamus, that induces adrenocorticotropic hormone release from the anterior pituitary and subsequent cortisol synthesis in the adrenal glands. Norepinephrine released from locus coeruleus will feedback to inhibit its production, and corticotropin-releasing factor will feedback to inhibit its production, while positively feeding to the locus coeruleus to increase norepinephrine production. The LC's role in cognitive function in relation to stress is complex and multi-modal. Norepinephrine released from the LC can act on α2 receptors to increase working memory, or an excess of NE may decrease working memory by binding to the lower-affinity α1 receptors. Psychiatric research has documented that enhanced noradrenergic postsynaptic responsiveness in the neuronal pathway (brain circuit) that originates in the locus coeruleus and ends in the

basolateral nucleus The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment (t ...

of the

is a major factor in the pathophysiology of most stress-induced fear-circuitry disorders and especially in

posttraumatic stress disorder Post-traumatic stress disorder (PTSD) is a mental and behavioral disorder that can develop because of exposure to a traumatic event, such as sexual assault, warfare, traffic collisions, child abuse, domestic violence, or other threats on ...

(PTSD). The LC neurons are probably the origin of the first or second "leg" of the "PTSD circuit." An important 2005 study of deceased American army veterans from World War II has shown combat-related PTSD to be associated with a postmortem-diminished number of neurons in the locus coeruleus (LC) on the right side of the brain.

In opiate withdrawal

Opioid Opioids are substances that act on opioid receptors to produce morphine-like effects. Medically they are primarily used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioi ...

s inhibit the firing of neurons in the locus coeruleus. When opioid consumption is stopped, the increased activity of the locus coeruleus contributes to the symptoms of opiate withdrawal. The α₂ adrenergic receptor agonist

clonidine Clonidine, sold under the brand name Catapres among others, is an α2-adrenergic agonist medication used to treat high blood pressure, ADHD, drug withdrawal ( alcohol, opioids, or nicotine), menopausal flushing, diarrhea, spasticity, an ...

is used to counteract this withdrawal effect by decreasing adrenergic neurotransmission from the locus coeruleus.

Rett syndrome

The genetic defect of the transcriptional regulator MECP2 is responsible for Rett syndrome. A MECP2 deficiency has been associated to catecholaminergic dysfunctions related to autonomic and sympathoadrenergic system in mouse models of Rett Syndrome (RTT). The locus coeruleus is the major source of noradrenergic innervation in the brain and sends widespread connections to rostral (cerebral cortex, hippocampus, hypothalamus) and caudal (cerebellum, brainstem nuclei) brain areasHokfelt T, Martensson R, Bjorklund A, Kleinau S, Goldstein M. 1984. Distribution maps of tyrosine-hydroxylase-immunoreactive neurons in the rat brain. In Handbook of Chemical Neuroanatomy, Vol. 2. Classical Transmitters in the CNS, Part I ( A. Bjorklund and T. Hokfelt, eds.) pp. 277-379. Elsevier, New York. and. Indeed, an alteration of this structure could contribute to several symptoms observed in MECP2-deficient mice. Changes in the electrophysiological properties of cells in the locus ceruleus were shown. These Locus Coeruleus cell changes include hyperexcitability and decreased functioning of its noradrenergic innervation. A reduction of the tyrosine hydroxylase (TH) mRNA level, the rate-limiting enzyme in catecholamine synthesis, was detected in the whole pons of MECP2-null male as well as in adult heterozygous female mice. Using immunoquantification techniques, a decrease of TH protein staining level, number of locus coeruleus TH-expressing neurons and density of dendritic arborization surrounding the structure was shown in symptomatic MECP2-deficient mice. However, locus coeruleus cells are not dying but are more likely losing their fully mature phenotype, since no apoptotic neurons in the pons were detected. Researchers have concluded that, "Because these neurons are a pivotal source of norepinephrine throughout the brainstem and forebrain and are involved in the regulation of diverse functions disrupted in Rett Syndrome, such as respiration and cognition, we hypothesize that the locus coeruleus is a critical site at which loss of MECP2 results in CNS dysfunction. Restoration of normal locus ceruleus function may therefore be of potential therapeutic value in the treatment of Rett Syndrome." This could explain why a norepinephrine reuptake inhibitor ( desipramine, DMI), which enhances the extracellular NE levels at all noradrenergic synapses, ameliorated some Rett syndrome symptoms in a mouse model of Rett syndrome.

Neurodegenerative diseases

The locus ceruleus is affected in many forms of neurodegenerative diseases: genetic and idiopathic

, progressive supranuclear palsy, Pick's disease or Alzheimer's disease. It is also affected in

Down syndrome Down syndrome or Down's syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is usually associated with child development, physical growth delays, mild to moderate ...

.Esiri MM. et al. (2004). Neuropathology of dementia. 2nd ed. Cambridge University Press. For example, there is up to 80% loss of locus ceruleus neurons in Alzheimer's disease, Mouse models of Alzheimer's disease show accelerated progression after chemical destruction of the locus ceruleus, and neurofibrillary tangles, a primary biomarker of Alzheimer's disease, may be found in the locus ceruleus decades before any clinical symptoms. The norepinephrine from locus ceruleus cells in addition to its neurotransmitter role locally diffuses from "varicosities". As such it provides an endogenous

anti-inflammatory Anti-inflammatory is the property of a substance or treatment that reduces inflammation or swelling. Anti-inflammatory drugs, also called anti-inflammatories, make up about half of analgesics. These drugs remedy pain by reducing inflammation as ...

agent in the microenvironment around the neurons, glial cells, and blood vessels in the neocortex and hippocampus. It has been shown that norepinephrine stimulates mouse microglia to suppress Aβ-induced production of

cytokine Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in a ...

s and promotes

phagocytosis Phagocytosis () is the process by which a cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs phagocytosis i ...

of Aβ. This suggests that degeneration of the locus ceruleus might be responsible for increased Aβ deposition in AD brains. Degeneration of pigmented neurons in this region in Alzheimer's and Parkinson's disease can be visualized in vivo with Neuromelanin MRI. Since the marked degeneration of locus coeruleus, and the neuroprotective properties of noradrenaline, Ian Robertson proposed the "''Noradrenergic Theory of Cognitive Reserve''" which postulates that the upregulation of the locus coeruleus-noradrenergic system throughout the lifespan may enhance cognitive stimulation contributing to cognitive reserve preventing from neurodegeneration. Recent evidence appear to support this theory reporting the locus coeruleus integrity primarily responsible of biological brain maintenance, cognitive efficiency, and reduced neuropathological burden.

Sleep deprivation

Animal studies showed that sleep deprivation can reduce the number of neurons in the locus coeruleus. Therefore the possibility of lasting damages to human brain functions due to sleep deprivation has become a matter of discussion.

History

The locus coeruleus was discovered in 1784 by Félix Vicq-d'Azyr, redescribed later by Johann Christian Reil in 1809 and named by the brothers Joseph and Karl Wenzel in 1812.Swanson, LW. Neuroanatomical terminology : a lexicon of classical origins and historical foundations. Oxford University Press, 2014. England High monoamine oxidase activity in the rodent LC was found in 1959, monoamines were found in 1964 and the widespread projections of noradrenergic neurons in the 1970s. An important advance in understanding the anatomical organization of the locus coeruleus was the application of the

Falck-Hillarp technique The Falck-Hillarp method of fluorescence (the F-H method) is a technique that makes it possible to demonstrate and study, with unique precision and susceptibility, certain monoamines, among those the three catecholamines dopamine, noradrenaline, and ...

, which combines freeze-dried tissue and formaldehyde to cause catecholamines (such as norepinephrine) and serotonin to fluoresce in tissue sections.

Etymology

''Coeruleus or caeruleus''

The 'English' name ''locus coeruleus''Anderson, D.M. (2000). ''Dorland's illustrated medical dictionary'' (29th edition). Philadelphia/London/Toronto/Montreal/Sydney/Tokyo: W.B. Saunders Company. is actually a Latin expression consisting of the noun, ''locus'', "place" or "spot"Lewis, C.T. & Short, C. (1879). ''A Latin dictionary founded on Andrews' edition of Freund's Latin dictionary.'' Oxford: Clarendon Press. and the adjective ''coeruleus'', "dark blue" or "sky-blue".Kraus, L.A. (1844). ''Kritisch-etymologisches medicinisches Lexikon'' (Dritte Auflage). Göttingen: Verlag der Deuerlich- und Dieterichschen Buchhandlung.Foster, F.D. (1891-1893). ''An illustrated medical dictionary. Being a dictionary of the technical terms used by writers on medicine and the collateral sciences, in the Latin, English, French, and German languages.'' New York: D. Appleton and Company. This was aptly translated into English as ''blue place'' in 1907 in the English translationBarker, L.W. (1907). ''Anatomical terminology with special reference to the NA With vocabularies in Latin and English and illustrations.'' Philadelphia: P. Blakiston's Son & Co. of the official Latin anatomic nomenclature of 1895, '' Nomina Anatomica''. The name of the ''locus coeruleus'' is derived from its azure appearance in unstained brain tissue. The color is due to light scattering from neuromelanin in noradrenergic (producing norepinephrine) nerve cell bodies. The spelling ''coeruleus'' is actually considered incorrect,Triepel, H. (1910). ''Die anatomischen Namen. Ihre Ableitung und Aussprache. Mit einem Anhang: Biographische Notizen.''(Dritte Auflage). Wiesbaden: Verlag J.F. Bergmann. with dictionaries of classical Latin preferring ''caeruleus''Wageningen, J. van & Muller, F. (1921). ''Latijnsch woordenboek.'' (3de druk). Groningen/Den Haag: J.B. Wolters' Uitgevers-Maatschappij instead. ''Caeruleus'' is derived from ''caelum'', hence the spelling with -ae, like caeluleus → caeruleus. ''Caelum'' in classical Latin could refer to ''the sky'', ''the heaven'' or ''the vault of heaven''. In mediaeval Latin, orthographic variants such as ''coelum''Niermeyer, J.F. (1976). ''Mediae Latinitatis lexicon minus.Lexique Latin médiéval-Français/Anglais. A medieval Latin-French/English dictionary.'' Leiden: E.J. BriLL. for classical Latin ''caelum'' and ''cerulans'' for classical Latin ''caerulans'' can be found. In English, the color adjective ''cerulean'' is derived from Latin ''caeruleus''.Donald, J. (1880). ''Chambers's etymological dictionary of the English language.'' London/Edinburgh: W. & R. Chambers. In addition, '' ceiling'' is ultimately derived from Latin ''caelum''.Klein, E. (1971). A comprehensive etymological dictionary of the English language. Dealing with the origin of words and their sense development thus illustration the history of civilization and culture. Amsterdam: Elsevier Science B.V.

''Official Latin nomenclature''

The official Latin nomenclature, '' Nomina Anatomica'' as ratified in

Basel , french: link=no, Bâlois(e), it, Basilese , neighboring_municipalities= Allschwil (BL), Hégenheim (FR-68), Binningen (BL), Birsfelden (BL), Bottmingen (BL), Huningue (FR-68), Münchenstein (BL), Muttenz (BL), Reinach (BL), Riehen (BS) ...

in 1895His, W. (1895). ''Die anatomische Nomenclatur. Nomina Anatomica. Der von der Anatomischen Gesellschaft auf ihrer IX. Versammlung in Basel angenommenen Namen''. Leipzig: Verlag Veit & Comp. and in

Jena Jena () is a German city and the second largest city in Thuringia. Together with the nearby cities of Erfurt and Weimar, it forms the central metropolitan area of Thuringia with approximately 500,000 inhabitants, while the city itself has a po ...

in 1935Kopsch, F. (1941). ''Die Nomina anatomica des Jahres 1895 (B.N.A.) nach der Buchstabenreihe geordnet und gegenübergestellt den Nomina anatomica des Jahres 1935 (I.N.A.)'' (3. Auflage). Leipzig: Georg Thieme Verlag.Stieve, H. (1949). ''Nomina Anatomica. Zusammengestellt von der im Jahre 1923 gewählten Nomenklatur-Kommission, unter Berücksichtigung der Vorschläge der Mitglieder der Anatomischen Gesellschaft, der Anatomical Society of Great Britain and Ireland, sowie der American Association of Anatomists, überprüft und durch Beschluß der Anatomischen Gesellschaft auf der Tagung in Jena 1935 endgúltig angenommen.'' (4th edition). Jena: Verlag Gustav Fischer. contained the orthographically correct form ''locus caeruleus''. The ''Nomina Anatomica'' published in 1955International Anatomical Nomenclature Committee (1955). ''Nomina Anatomica'' . London/Colchester:Spottiswoode, Ballantyne and Co. Ltd. inadvertently introduced the incorrect spelling ''locus coeruleus'', without further explanation. The subsequent edition monophthongized the

diphthong A diphthong ( ; , ), also known as a gliding vowel, is a combination of two adjacent vowel sounds within the same syllable. Technically, a diphthong is a vowel with two different targets: that is, the tongue (and/or other parts of the speech ...

, resulting in ''locus ceruleus'',Donáth, T. & Crawford, G.C.N. (1969). ''Anatomical dictionary with nomenclature and explanatory notes.'' Oxford/London/Edinburgh/New York/Toronto/Syney/Paris/Braunschweig: Pergamon Press. as they proclaimed that: "All diphthongs should be eliminated".International Anatomical Nomenclature Committee (1966). ''Nomina Anatomica''. Amsterdam: Excerpta Medica Foundation. This form was retained in the subsequent edition. The following two editions from 1977International Anatomical Nomenclature Committee (1977). ''Nomina Anatomica, together with Nomina Histologica and Nomina Embryologica''. Amsterdam-Oxford: Excerpta Medica. and 1983International Anatomical Nomenclature Committee (1983). ''Nomina Anatomica, together with Nomina Histologica and Nomina Embryologica''. Baltimore/London: Williams & Wilkins reverted the orthography back to the incorrect spelling ''locus coeruleus'', while the subsequent edition from 1989International Anatomical Nomenclature Committee (1989). ''Nomina Anatomica, together with Nomina Histologica and Nomina Embryologica''. Edinburgh: Churchill Livingstone. eventually returned to the correct spelling ''locus caeruleus''. The current edition of the ''Nomina Anatomica'', rebaptized as '' Terminologia Anatomica'',Federative Committee on Anatomical Terminology (FCAT) (1998). ''Terminologia Anatomica''. Stuttgart: Thieme dictates ''locus caeruleus'' in its list of Latin expressions and correspondingly mentions ''locus caeruleus'' in its list of English equivalents. This is in line with the statement made by the chairman of the ''Terminologia Anatomica'' that "the committee decided that Latin terms when used in English should be in correct Latin".

References

A novel based upon real facts by Max Trasin, Pentian 2016

External links

"A Lecture, Higher Brain Function: Activation of the Brain and Levels of Consciousness"
at East Tennessee State University *
Diagram
at

University of Texas at Austin The University of Texas at Austin (UT Austin, UT, or Texas) is a public research university in Austin, Texas. It was founded in 1883 and is the oldest institution in the University of Texas System. With 40,916 undergraduate students, 11,075 ...

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University of Virginia The University of Virginia (UVA) is a public research university in Charlottesville, Virginia. Founded in 1819 by Thomas Jefferson, the university is ranked among the top academic institutions in the United States, with College admission ...

* https://web.archive.org/web/20070512234228/http://www2.umdnj.edu/~neuro/studyaid/Practical2000/Q45.htm {{DEFAULTSORT:Locus Coeruleus Pons Norepinephrine

Anatomy

Connections

Inputs

Outputs

Function

Pathophysiology

In stress

In opiate withdrawal

Rett syndrome

Neurodegenerative diseases

Sleep deprivation

History

Etymology

''Coeruleus or caeruleus''

''Official Latin nomenclature''

See also

References

External links